Intervention to increase exercise in drug dependent patients represents a potentially useful yet unexplored strategy for preventing relapse. There are currently no established exercise interventions for use with this population. The long-term objectives of this research program are to improve treatment options for drug dependent patients by developing and establishing the efficacy of a supervised aerobic exercise intervention and to advance knowledge of the relationship between physical activity and substance use outcomes. In the present application, we propose to develop a supervised aerobic exercise (SAE) intervention for drug dependent patients and to conduct a preliminary, randomized clinical trial, examining its efficacy in comparison to a brief advice (BA) exercise intervention. In the first phase of this project (Year 1), we will develop and pilot the SAE intervention with 20 patients completing an intensive day and evening alcohol and drug treatment program. We will also develop a behavioral component to promote exercise adherence, including clinician and patient manuals. In the second phase (Years 2 & 3) we will conduct a preliminary, randomized trial with 50 sedentary drug dependent patients to examine the efficacy of the SAE intervention relative to the BA comparison condition over a six-month follow-up period. We expect that, relative to the BA condition, participants randomized to the SAE condition will demonstrate better substance use outcomes as well as improved mood, depressive symptoms, and cardiorespiratory fitness. If the efficacy of this intervention can be established in this trial and in subsequent clinical trials, drug dependent patients will be provided with a valuable adjunct or alternative to traditional substance abuse treatment.